Accumulator



Nov. 19, 1968 c, THOMPSON ET AL 3,411,319

ACCUMULATOR 2 Sheets-Sheet 1 Filed Aug. 1, 1966 m l m My m v 4 BY M/ZZZl/l ('5 array/vino? c. H. THOMPSON ET AL 3,411,319

Nov. 19, 1968 ACCUMULATOR 2 Sheets-Sheet 2 Filed Aug. 1, 1966 United States Patent Office 3,411,319 Patented Nov. 19, 1968 3,411,319 ACCUMULATOR Chester H. Thompson, Xenia, and William C. Schollenberger, Dayton, Ohio, assignors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Filed Aug. 1, 1966, Ser. No. 569,218 2 Claims. (Cl. 62503) ABSTRACT OF THE DISCLOSURE Accumulator formed of a cylindrical hollow body, an inlet tube extending from the upper end of the body toward the lower end thereof adjacent the body wall, the lower end of the tube being closed, an elongated slot in the tube opening toward the wall, and an outlet in the upper end of the accumulator.

This invention relates to accumulators, and more particularly to an accumulator adapted for use in refrigeration systems such as heat pump, air conditioning and commercial freezing systems, for example.

It is well known that compressors used in refrigeration systems are not designed for receiving, nor can they handle, significant amounts of liquid refrigerant without eventual and possibly severe damage to the compressor parts. The compressor parts, such as the pistons, move very rapidly, and the velocity of the refrigerant flow through the suction and discharge valving is very high. Thus, if liquid refrigerant enters into the compressor, it will, due to the incompressible characteristics of liquids, act as a substantially solid mass and cause damaging forces to be created in the compressor parts. This problem is well recognized in the refrigeration art and various means have been proposed to cope with it.

One method used to prevent the return of liquid refrigerant to the compressor of a refrigeration system involves the use of a heat exchanger in the suction return line to assure the return of dry gas to the compressor. The heat exchanger has to be carefully designed to avoid excessive pressure loss and to insure efiicient transfer of heat. The heat exchanger itself not only increases the cost of production, but the actual designing thereof may be expensive.

Another system utilized to prevent the return of liquid refrigerant to the compressor, and the type of system to which this invention applies, includes the use of a suction accumulator. These accumulators provide a space where the liquid refrigerant and oil can be delayed and broken up into gas. Such accumulators must be capable of metering all of the refrigerant and oil back into the system when the refrigerant and oil are required by the prevailing conditions under which the system is operating. These conditions may be either or both internal or external (cooling or heating requirements, ambient temperatures, etc), to the system. On heat pump refrigeration equipment it is particularly necessary to provide some means to store refrigerant because there is a certain outdoor temperature at which the normal refrigerant charge becomes excessive. This excess refrigerant must be stored so that it will not enter the compressor and cause damage to the latter.

Prior known accumulators have not been altogether satisfactory because they would not always prevent liquid refrigerant from being drawn into the suction line to the compressor. The liquid and gas mixture of refrigerant and oil enters such accumulators at a relatively high velocity and causes turbulence within the accumulator. This turbulence results in a liquid-gas mist or fog which includes liquid droplets. In addition, the high velocity of the mixture may cause liquid refrigerant to be splashed toward the suction outlet. In any event, liquid refrigerant may easily be drawn into the suction line with resultant damage to the compressor. The turbulence may be exceptionally severe when a substantial amount of liquid refrigerant is being stored in the accumulator during the cold winter periods when the accumulator is used in heat pump equipment.

Accordingly, among the several objects of this invention is to provide an accumulator for refrigeration systems which is adapted to reduce turbulence substantially in the accumulator so that liquid refrigerant will not enter the suction line and be delivered to the compressor.

Another object of this invention is to provide an accumulator of the class described, which, when utilized in a heat pump system, is adapted to trap and hold back refrigerant which would otherwise enter the compressor when the reversing valve of the heat pump system changes the refrigerant flow from a cooling cycle flow to a heating cycle fiow.

A further object of this invention is to provide an accumulator of the class described which assures a dry compressor operation over the complete range of heating and cooling operation and eliminates liquid refrigerant pumping.

Still another object of this invention is to provide an accumulator such as described which assumes longer and more trouble-free compressor life than previously known conventional designs, and which may also be of a smaller capacity than conventional designs.

Another object of the present invention is to provide an accumulator of the type described which permits the compressor to operate at maximum capacity with a saturated evaporator coil without the aid of a heat exchanger.

A further object of the present invention is to provide an accumulator such as described which is adapted to reduce the velocity of the refrigerant and oil as they enter the accumulator.

Still another object of this invention is to provide an accumulator of the class described which is simple and economical in construction and effective in operation.

Other objects and features of this invention will become apparent as the description progresses.

In the accompanying drawings, in which one embodiment of this invention is illustrated,

FIG. 1 is a front elevation of an accumulator constructed according to this invention, certain parts being broken away and shown in section for clarity;

FIG. 2 is a plan view of the accumulator shown in FIG. 1;

FIG. 3 is a side elevation of one component of the accumulator shown in FIG. 1; and

FIG. 4 is a diagrammatic illustration of a heat pump system showing the location of an accumulator of this invention.

Throughout the several views of the drawings like parts are indicated by corresponding reference characters.

Referring now to the drawings, an accumulator of this invention is generally indicated at 1. Accumulator 1 includes a cylinder, shell or hollow body 3 having end caps 5 and 7 secured, as by welding for example, on its opposite ends. End cap 5 is formed with a first opening 9 into which a suction line fitting 11 is adapted to fit. A second opening 13 is provided in end cap 5 through which the inlet end of an elongated hollow member or distributor tube 15 extends. Distributor tube 15 extends adjacent to but spaced a slight distance from the wall of cylinder 3 all the way from end cap 5 to a point adjacent end cap 7. As will be made apparent hereinafter, tube 15 forms a refrigerant delivery passage into the interior of cylinder 3.

The inlet end of distributor 15 is flared slightly as indicated at 17 to increase the diameter of the tube. The opposite or inner end of the distributor 15 is preferably closed by plugging, capping, crimping or other suitable means. The tube 15 is provided with a liquid refrigerant escape opening in the form of an elongated lateral slot 19 extending longitudinally of the tube and opening toward the wall of the cylinder.

An accumulator 1 of this invention is shown as it might appear when used in a heat pump system in FIG. 4. As shown, the heat pump system includes an indoor coil or heat exchanger 21 and an outdoor coil or heat exchanger 23. Although not shown, provision would be made for conveying air over the coil 21 and delivering the air to the enclosure to be air conditioned or heated. The coil 21 serves as the evaporator during cooling operation and as the condenser during heating operation. The outside coil 23 serves as the condenser during cooling operation and as the evaporator during heating operation. Provision is also made for conveying outside air over the coil 23 and discharging the same to outdoors or to some other place exterior of the enclosure to be air conditioned or heated.

One end of coil 23 is connected by a line 25 to one end of coil 21. Line 25 includes a check valve 27, drierstrainer 29 and pan heater 31. A heating capillary tube 33 is also provided lay-passing check valve 27 and drierstrainer 29. The other end of coil 23 is connected to one port a reversing valve 35 by a line 36. The other end of coil 21 is connected to a second port of reversing valve 35 by a line 37. A line 39 connects a third port of reversing valve 35 to the inlet end of the distributor 15 of accumulator 1. The outlet opening 9 of accumulator 1 is connected by a suction line 41 to the intake port of a compressor 43. The discharge outlet of the compressor is connected by a line to a fourth port of reversing valve 35. It will be understood that in addition to a charge of refrigerant in the system, some oil or lubricant will also be present in the refrigerant. This oil emanates from the compressor crankcase. It is virtually impossible to prevent small quantities of oil from passing out of the compressor with the discharge gas. However, the circulation of some oil does not seriously detract from the performance of the system, but rather, may be desirable because it reduces noise and lubricates parts not otherwise accessible. The refrigeration system must be designed, and the accumulator 1 of this invention is designed, to effectively return all oil put into circulation by the compressor.

When the heat pump system is functioning to cool the enclosure in which coil 21 is located all or a very substantial portion of the normal charge of refrigerant will be utilized by the system. Condensed refrigerant flows from coil 23, which acts as a condenser, through line 25 to coil 21.

As the refrigerant passes through coil 21 all or a substantial portion of it vaporizes as heat is removed from the air passing over the coil. The refrigerant then passes through line 37 and reversing valve 35 to line 39 which delivers the refrigerant to the distributor tube 15. The refrigerant at this point is primarily in the form of vaporized refrigerant, but may also include liquid particles or droplets of refrigerant, as well as oil entering the system at the compressor.

The mixture of gas refrigerant, liquid refrigerant, if present, and oil enters the upper end of distributor tube 15. The velocity of the mixture is reduced slightly as the mixture passes from the tube inlet through the flared portion 17 to the larger cross section of the tube. Neverthe- 4 less, the velocity of the mixture may still be relatively high at this point, resulting in turbulence in the tube. However, this turbulence is expended within the tube and the mixture exits from the tube 15 through slot 17 and is directed toward the cylinder Wall.

It will be seen that the presence of any liquid refrigerant or oil is prevented from causing turbulence in the cylinder 3 adjacent the suction outlet of the accumulator by the distributor tube 15, the slot or opening 17 and the location of the tube and slot relative to the cylinder wall. Thus, if any liquid refrigerant is present during a cooling operation, such as might occur if the system is overcharged with refrigerant or if vaporization in coil 21 is incomplete, it is prevented from being drawn through the suction line 41 to the compressor. Since substantially all of the refrigerant charge is utilized during a cooling operation, it is unlikely that any quantity of liquid refrigerant would accumulate in the bottom of the cylinder 3 unless the system is overcharged with refrigerant. However, the accumulator would still prevent the delivery of liquid into the suction line 41 as explained hereinafter during a discussion of a heating operation.

T 0 complete its circuit during a cooling operation, the gaseous refrigerant and the oil mixed therewith are drawn to the compressor 43 through line 41. The refrigerant, after compression, is discharged through line 45 and fiows through the reversing valve 35 and line 36 back to the coil 23.

When the heat pump system is functioning to heat the enclosure in which coil 21 is located, the full charge of refrigerant is not needed. This is due to the fact that the range of environmental air temperatures for the coils 21 and 23 is confined to a generally lower level for winter operation than for summer operation, and the compressor will pump refrigerant at a lower rate, weightwise, during winter operation. This reduction of compressor pumping rate results in an excess of liquid refrigerant which must be prevented from entering the compressor.

Starting with the compressor 43, the compressed re frigerant gas flows through line 45, reversing valve 35, and line 37 to coil 21, which acts as a condenser, where heat is taken from the refrigerant and the latter is condensed. The condensed refrigerant then flows through line 25 and heating capillary tube 33 to coil 23 which acts as an evaporator. However, due to the ambient temperature, not all of the liquid refrigerant may be evaporated and the refrigerant may leave the evaporator as a mixture of gas and liquid. This mixture, which includes any oil added to the system by the compressor, passes through line 36, reversing valve 35 and line 39 into the upper end of distributor tube 15. The mixture enters the tube at a relatively high velocity, which is reduced slightly as the mixture passes through the flared portion 17, and then plunges down the tube where the turbulence of the mixture is expended. The mixture of refrigerant and oil then passes at a relatively low velocity out of the tube 15 through slot 19.

Since not all of the refrigerant charge is utilized at the same time during a heating operation, the liquid refrigerant accumulates in the bottom of the cylinder 3. Generally speaking, as the outside temperature drops more liquid refrigerant will accumulate in the bottom of the cylinder. As the liquid refrigerant level rises above the bottom of slot 19, the mixture entering the tube slams into the liquid within the tube and creates turbulence therein. This turbulence is dissipated in the tube and does not cause any significant turbulence in the liquid refrigerant outside the tube 15. Thus the liquid refrigerant outside the tube remains relatively calm. The low pressure in the upper end of the accumulator created by suction line 41, causes the calm liquid refrigerant to vaporize and be pulled into the line 41, as well as causing the gaseous or vaporized refrigerant, which entered the upper end of tube 15 and was dispensed therefrom through slot 19 above the liquid level, to be pulled toward the suction line. In addition any particles of oil are also pulled into the suction line so that a mixture of refrigerant gas and oil is delivered to the compressor. As shown in FIG. 4, the level of liquid refrigerant has risen approximately to the half full point of the accumuflator. This liquid level may be representative of a certain ambient temperature and may vary as the ambient temperature changes. However, regardless of the level of liquid refrigerant of the accumulator, turbulence due to the velocity of the mixture entering the tube 15 is dissipated within the tube, and the liquid refrigerant outside tube 15 remains relatively calm so that it will not be delivered through line 41 in as a liquid to the compressor.

Although the accumulator is shown and described herein in connection with a heat pump refrigeration system, it will be understood that it may be used in other refrigeration systems such as residential and commercial air conditioning, commercial freezers, automobile air conditioning etc., where it is essential to prevent delivery of liquid refrigerant to the compressor.

It will thus be seen that the accumulator of this invention is adapted to reduce turbulence therein so that liquid refrigerant will not be delivered to the compressor.

In view of the foregoing, the several objects and other advantages are achieved.

It will be understood that the invention is not to be limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined in the appended claims.

We claim:

1. An accumulator for a refrigerant system comprising a hollow body, said body having an outlet, means forming a refrigerant delivery passage into the interior of said body, said means having a lateral opening therein through which refrigerant can escape, said opening being located so that refrigerant escaping from said means is directed away from said outlet and toward one wall of said hollow body, said outlet being located at the upper end of the accumulator, said means comprising an elongated hollow member extending adjacent a side wall of said body from adjacent the upper end of said body toward the lower end thereof, and said opening being formed as an elongate longitudinally extending slot in said hollow member.

2. An accumulator for a refrigerant system comprising a hollow body, said body having an outlet, means forming a refrigerant delivery passage into the interior of said body, said means having a lateral opening therein through which refrigerant can escape, said opening being located so that refrigerant escaping from said means is directed away from said outlet and toward one wall of said hollow body, said outlet being located at the upper end of the accumulator, said means comprising an elongated hollow member extending adjacent a side wall of said body from adjacent the upper end of said body toward the lower end thereof, and said elongated hollow member having a flared portion adjacent the upper end thereof to provide a larger cross sectional interior area below the flared portion than above the flared portion.

References Cited UNITED STATES PATENTS 2,637,983 5/1953 Malkoff et al. 62-287 2,787,135 4/1957 Smith 62-113 ROBERT A. OLEARY, Primary Examiner. 

